The String.isEmpty function tests the length of a given string
to determine if it is empty and returns a boolean value. If the string
has zero length, true is returned. if the string has a length greater
than zero, false is returned.

Note that you can use the String.length function to find the numeric
length of a string.

The mandatory string parameter can be any string containing zero
or more of any combination of characters (including white spaces). This
parameter can also be an empty string.